The ceramic coating was prepared by micro arc oxidation on A356 in NaOH–Na2SiO3 electrolyte. The influence of concentration of sodium hydroxide on the arcing anodic voltage, the rate of ceramic coatings formation and its corrosion resistance were investigated. The result shows that the arcing anodic voltage is reduced to 230 V from 350 V, corrosion resistance time is increased to 25 min from 19 min, while the concentration of sodium hydroxide rises 5 g/L from 1 g/L; the formation rate of ceramic coatings is...